Manchester Memoirs, Vol. xlvi. (1902), No. \%. 



XII. The Chatham Islands : a Study in Biology. 



A Lecture delivered, by invitation of the Council, on March 

 4th, ig02. 



By Arthur Dendy, D.Sc, 



Professor of Biology in the Canterhiry College, University of New Zealaiia. 



Ever since the publication of Wallace's famous work 

 on " Island Life," the study of insular faunas and floras 

 has attracted special attention from biologists, and it has 

 been clearly recognised that the fundamental laws which 

 govern the geographical distribution of plants and animals 

 receive their best illustration in such rigidly circum- 

 scribed areas as may be included under the term ' Island,' 

 where the number of species to be studied is less over- 

 whelming than on continents, and where the geographical 

 isolation gives full play to the powers of variation. 



The time-honoured classification of islands into two 

 great groups — continental and oceanic — is undoubtedly 

 extremely useful, but, like all other systems of classifica- 

 tion, it occasionally breaks down. New Zealand, for 

 example, is thoroughly oceanic in the character of its 

 fauna — in the absence of indigenous mammalia (with the 

 exception of rats and bats), the total absence of snakes 

 and the almost complete absence of amphibia, and no 

 less in the extremely high degree of peculiarity amongst 

 those animals and plants which it does possess ; but, on 

 the other hand, its geological characters are continental — 

 it is not entirely of volcanic formation, but contains 

 sedimentary rocks dating back to palaeozoic times, while 



Mav lolh, I go 2. 



